Apparatus for effecting heat transfer



1,617,609 Feb. 15, 1927. H F SMITH A APPARATUS FOR EFFECTING HEAT TRANSFER Filed Marci; 16, 1922 l Patented Feb. 15, 1927.

UNITED HARRY rf SMITH, or

APPARATUS FOR EFFEGTING HEAT TRANSFER.

Appnoaaon med March 1s, 1922. seril no. 544,255.

This ,invention relates to furnaces.

One ofthe principal objects of the inven- 'tion is to provide a method of heat i nterchange, applicable to furnaces, and the like,

and apparatus adapted for the carrying on of that method` Other objects and advantages of the invention will be apparent from thev descript'ion set out below when taken in connection with the accompanying drawing.

Inthe transfer of heat from a gas, `or a mixtureof gases, to a bodythe rate of heat transfer is dependent upon the differential.

temperature which exists between the heated gases and the body to be'heated, and-the 'quanity of heated gases which are broughtl highest flame temperature possible, and toA passthe resulting hot products of combustion into the furnace, on one side of the hearth and out ofthe furnace on the other side of the hearth, this construction being such that the hot products of combustion pass across the hearth and the material resting thereon giving up heat to that material on the way. In this lconventional construction the temperature immediately adjacent the 40 point of ingress of the hot products of comimmediately adjacent the point of egress, 1 and the material is, therefore', not uniformly heated. i

In'the invention forming the subject matter hereof, the furnace' isprovided with a heating chamber Aof small capacity, means'being provided for `forcing the hot products of coi'nbustionthrough this chamber and over the hearthl at a' comparativelyv high] velocity,

weight ofthe heated gases will' be'brought into contact'with the m'aterialtobe heated. Since such a largequantity lofl the hot products 'of 1 combustion is brought into' contactwith' the; 'bQdy being @heatedv it s het which is efficient and simple in operation,

bustion is much higher than the temperaturesofthat fora given time interval', a" largev drawing.

necessary, ordesirablathat the temperature orner..

DAYTON, OHIO, ASSIGNOR TO THE GAS RESEARCH COMPANY, 0F DAYTON, OHIO, A CORPORATION OF OHIO.

of the productsy of combustion be extremely g high, inasmuch as the same heat transfer can be secured Without a very high temperature differential, as would be secured where the temperature of they hot" gases is much higher but a smaller weight of gases is brought into contact with the material -'being heated; In practicing the method of heat transfer, according to 4this invention, the

ranged that considerable quantities of the hot products of combustion will' be mixed with the incoming heated products of combustion and the mixture caused to circulate Vat .high velocity through the heating chamber, and over the hearth. Y

In the drawing, herewith, in which like characters of reference designate like parts throughout the several views thereof,

Fig. 1, is a nace constructed in accordance with this invention, the furnace being shown constructed of suitable brick, or analogous ma terial; and

heating' chamber of the furnace is so ar.-

sectional view through a fur- Fig. 2, is a slightly modified form of construction.

Considering first the modification shown in Fig. 1, the numeral 10 designates the top wall of the furnace. Spaced from the top wall. a suitable distance is'an arch or cross wall 11, which serves as'the hearth to receive the material to be heated, the space between the member 11 and the top 10constituting a heating chamber 12. The material to be heated isl introducedl into the heating chamber through a suitable door, or opening, not shown. Extending into the heating chamber 12, is a hollow refractory member 14, within which ispositioned the end of the pipe 15, adapted' to suppl amIxture of air and gas, or othersuita under pressure. The construction of the top wall -10 and theI hearth member `11 is such that the side-of the-.heating chamber le fuel,

which receives the refractoryvv member Mis flared,- as shown at 1K3 the other'side of the chamber -being correspondingly flared, as shown by the numerall, the heating chamb'er being thus 'in the nature of Venturi shape in cross section, as clearly" shown-in t e t The refractory member-"14 has its end suitably taperd,'asshown at 17 `-to fcp'r-l respond with the shape-ofthe flared gol-tion'l A15? f the'heating chamber 12 -Th eatmg 'W l2 will be very.' little highenthan the tem- 'perature at the outlet side 19. Consequently a uniform heating 'will be., securedthrough-` chamber also has opening therefrom an exhaust or vent pipe, 18.

Beneath the arch 11 is a passage 25, Pfeferably of considerably greater capacity than thechmber 12, which is connected at one end to the inlet side 13 of the chamber 12, and

@at the .other end to the outlet side of said chamber. The refractory member 14 is so 1 positioned that it extends across one end of the passage 25, the construction being such l that as the hot products of combustion issue from the" member` 14 under hi h Velocity and sweep across the hearth 11, t rough the chamber 12, they will tend to entrain and draw with them, through the passage the gases within that chamber. This construction constitutes in effect a jet pump. During operation the passage 25, therefore, will be under suction at one end while its other end will be under pressure, and there will be a circulation of a part of the hot products of combustion sweeping through the cham- -ber 12 down through the passage 25 into the ared end 13 of the chamber, Where these products of combustion will mix with the incoming highly heated roducts of combustion resulting from the urning of the mix` ture escaping from the pipe 15. All of the hot products of combustion, of course, will not be recireulated through the passage 25 and/ heating chamber 12, but during opera tion a certain ,roportion of the gases within the furnace will escape through the pipe 18 the amount of gas escaping through that i' pipe being just equivalent to the amount of turi shaped chamber 12 th\us bringing a large weight of heated gases per unit of time into Contact with the' material upon the hearth 11. Of course When the-furnace is first started the gaseswithinithe passage 25 .may be cold,

i. -but as the operation continues the walls of this chamberwill be very highly heated, so

that during 'continued' operationthe tem` perature at the inlet side'13 of the chamber out the furnace'and in addition, because of vthe large-weight of :gas that is brought into contact with the material4 to be heated, a very rapid heating will be secured. It

I -shouldbe noted that because of the small volumetric'capaclty of the heating chamber,

substantially all the' heated gases passing therethrough are brought into heat transferring contact with the 'material upon the hearth. Passing' thegases through the chamber under high velocity, therefore, will` insure bringing a large quantity, or large Weight, of these gases into contact with the material being heated.

The refractory member 14 is preferably made of such length that combust-ion of the fuel is practically completed Within that member so that only hot products of the combustion will issue from that member to mix with the products of combustion within the furnace; but of course this `is not essential. L I

In Fig. 2 is shown a slightly modified form ofconstructi-on, which differs from the form shown in Fig. 1 primarily in that the heating chamber and ,hearth carrying the material to be heated are so positioned that the hot products resulting from the combustion at the burner do notpass directly into the heating chamber. I

In this construction a combustible mixture .under pressure is introduced through the same angle as the tapered end ofthe refractory ,memben '-The other I.lend-of the passage opens into the passagef56, which 1n turn opens into the one side of the heating chamber 57. The other side of the heating chamber 57 has connected thereto a passage 58, substantially ,the same in construction as the passage 56, whichopens into the passage 59, which in turn is connected to the atmosphere and serves as a vent or exhaust p assage. Preferably a suitable flue 60, Whlch may be of any d-esired construction, is as` sociated with the outer end of -the assage 59 `to carry off the products of com ustion escaping therethrough.' The passage 55 is connected at one endl to the passage 58 and the vent passage 59, the refractory member extending across these passages. By means of this construction as products of combustion under considerable velocity issue from the end. of the refractory member 51 they will entrain and draw with them some of the gasesv within the passage'58. As a result there will be ai circulation of the hot products of combustion `through the passage 55, the passage 56, .the heating chamber 5? the passage 58 back intoA the passage 5,5 Afor recirculation. Part of the hot products of combustion will pass out 'through the vent and l passage 59, the amount escaping, .as is the case with the modification shown 1n Fig. 1, being governed by the quantity -o'f fresh `products ofvcombustion introduced from the burner.

In this construction, as in that described above in connection with Fig. 1, the combustible mixture being introduced under considerable pressure, a considerable velocity of flow is attained by the ingoing and recirculating products of combustion and, because of the comparatively small Acapacity of the heating chamber, this considerable velocity of flow is maintained within the heating chamber.' Consequently a large weight of hot gases 1s brought into contact with the material to be heated, for a given interval of time, and rapid heating of the material on the hearth of the heating chamber is therefore secured; Substantially.uniform temperature conditions being also attained within the heating chamber, as set out above.

While the method herein described, and the forms of apparatus for carrying this method into eect, constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise method and forms of apparatus, and

to said heating chamber, and a passage connecting the opposite sides of said heating chamber, said passage at one end terminating in cooperative relation with said nozzle, the construction being such that as hot products of combustion are introduced through the said nozzle, into said heating chamber,

under hi l1 velocity, to pass through said heating iamber, a part of thepreviously formed products of combustion will be caused to recirculate through the said passage back into the combustion chamber, another part of the products of combustion passing off through the vent pipe.

2. A furnace, of-the character'described, comprising a heating chamber vof small capacity', a flared inlet opening at vone side'.

ofthe heating chamber, a flared outlet opening at the other Vside of the heating chamber; a passage connecting the fla-red outlet opening and the flared inlet opening' a vent pipe connected to said chamber; an a'nozzle, through which products of combustion under pressure are introduced, positioned within said flared inlet open-ing, the construction being such that as the products of combustion pass from the said nozzle into the inlet opening and thence to the heating chamber, previously formed products of combustion will be entrained and drawn through the flared inlet opening into the heating chamber for admixture with the newly introduced hot products of combus tion.

3. A furnace, of the character described, comprising a heating chamber of small volumetric capacity, an inlet passage o enin into the heating chamber at one side t ereo an outlet passage opening from the heating chamber, said outlet passage being connected to the said inlet passage and also to a vent pipe; and a nozzle o ening into said inlet at its place of connection with the said outlet passage, the construction being such that as products of combustion under high velocity are introduced through said nozzle previously formed products of combustion will be entrained from the outlet passage and admixed with the newly formed hot products of combustion to be passed through the heatling chamber.

In testimony vvhereof ,I hereto aiix my signature.

, HARRY F. SMITH. 

